694 research outputs found

    Vortex Flows in the Solar Chromosphere -- I. Automatic detection method

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    Solar "magnetic tornadoes" are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that such rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role for the mass and energy transport in the solar atmosphere. For this purpose, we have developed a new automatic detection method for chromospheric swirls, i.e. the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike the previous studies that relied on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity which represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to 3D numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere revealed very abundant small-scale, short-lived chromospheric vortex flows that had not been found by visual inspection before.Comment: 12 pages, 9 figures, accepted for publication in A&

    Critical Behavior in Doping-Driven Metal-Insulator Transition on Single-Crystalline Organic Mott-FET

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    We present the carrier transport properties in the vicinity of a doping-driven Mott transition observed at a field-effect transistor (FET) channel using a single crystal of the typical two-dimensional organic Mott insulator κ\kappa-(BEDT-TTF)2_2CuN(CN)2_2Cl (κ\kappa-Cl).The FET shows a continuous metal-insulator transition (MIT) as electrostatic doping proceeds. The phase transition appears to involve two-step crossovers, one in Hall measurement and the other in conductivity measurement. The crossover in conductivity occurs around the conductance quantum e2/he^2/h , and hence is not associated with "bad metal" behavior, which is in stark contrast to the MIT in half-filled organic Mott insulators or that in doped inorganic Mott insulators. Through in-depth scaling analysis of the conductivity, it is found that the above carrier transport properties in the vicinity of the MIT can be described by a high-temperature Mott quantum critical crossover, which is theoretically argued to be a ubiquitous feature of various types of Mott transitions. [This document is the unedited Authors' version of a Submitted Work that was subsequently accepted for publication in Nano Letters, copyright \copyright American Chemical Society after peer review. To access the final edited and published work see http://dx.doi.org/10.1021/acs.nanolett.6b03817]Comment: 40 pages, 16 figures in Nano Letters, ASAP (2017

    A Study on Route Choice Model in the Case of Recreational Trip

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    This study aims to suggest an appropriate road improvement planning for regional exchange, with a view to regard recreational trip as main behavior of regional exchange. We have clarifyied how the facilities which will contribute to regional development influence route choice. This paper reported the results of the evaluation concerning the attractiveness of recreational facilities which influence route choice in case of a recreational trip, by quantification theory I, using the questionnaire data carried out in Fukui Prefectural TAN-NAN region. These results of analysis of attractive factors suggest that the model using the staying time has most applicable interpretation. However, further investigation on the grasp of the number of visitors is necessary

    A Study on Route Choice Model in the Case of Recreational Trip

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    This study aims to suggest an appropriate road improvement planning for regional exchange, with a view to regard recreational trip as main behavior of regional exchange. We have clarifyied how the facilities which will contribute to regional development influence route choice. This paper reported the results of the evaluation concerning the attractiveness of recreational facilities which influence route choice in case of a recreational trip, by quantification theory I, using the questionnaire data carried out in Fukui Prefectural TAN-NAN region. These results of analysis of attractive factors suggest that the model using the staying time has most applicable interpretation. However, further investigation on the grasp of the number of visitors is necessary

    Some Properties of 30KW-Class Electron Beam for Welding

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    Studies on Pheromones of Female Eri-Silk Moth, I. Preparation of C₆-C₁₁ 2-Alkenyl Triphenyiphosphonium Bromides

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    Article信州大学農学部紀要 20(1): 127-132(1983)departmental bulletin pape

    X-ray Emissions from Three-dimensional Magnetohydrodynamic Coronal Accretion Flows

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    We calculate the radiation spectrum and its time variability of the black hole accretion disk-corona system based on the three-dimensional magnetohydrodynamic simulation. In explaining the spectral properties of active galactic nuclei (AGNs), it is often assumed that they consist of a geometrically thin, optically thick disk and hot, optically thin corona surrounding the thin disk. As for a model of the corona, we adopt the simulation data of three-dimensional, non-radiative MHD accretion flows calculated by Kato and coworkers, while for a thin disk we assume a standard type disk. We perform Monte Carlo radiative transfer simulations in the corona, taking into account the Compton scattering of soft photons from the thin disk by hot thermal electrons and coronal irradiation heating of the thin disk, which emits blackbody radiation. By adjusting the density parameter of the MHD coronal flow, we can produce the emergent spectra which are consistent with those of typical Seyfert galaxies. Moreover, we find rapid time variability in X-ray emission spectra, originating from the density fluctuation produced by the magnetorotational instability in the MHD corona. The features of reflection component including iron fluorescent line emission are also briefly discussed.Comment: accepted to Publications of the Astronomical Society of Japa
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